Macroscopic and Microscopic Approaches ~ MECHTECH GURU

# Macroscopic and Microscopic Approaches

Microscopic approach uses the statistical considerations and  probability  theory,  where  we deal with “average” for all particles under consideration. This is the approach used in the disciplines known as kinetic theory and statistical mechanics.

In the macroscopic point of view, of classical thermodynamics, one is concerned with the time-averaged influence of many molecules that can be perceived by the senses and measured by the instruments.

The pressure exerted by a gas is an example of this.  It results from the  change  in momentum of the molecules, as they collide with the wall. Here we are not concerned with the actions of individual molecules but with the time-averaged force  on a given  area that can be measured  by a pressure gage.

From the macroscopic point of view, we are always  concerned with volumes that are very  large compared to molecular dimensions, and therefore a system (to be defined next) contains many molecules, and this is called continuum. The concept of continuum loses validity when the mean free path of molecules approaches the order of typical system dimensions

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